Method and apparatus for reducing fatigue resulting from viewing three-dimensional image display, and method and apparatus for generating data stream of low visual fatigue three-dimensional image

ABSTRACT

Provided is a method of reducing fatigue resulting from viewing a three-dimensional (3D) image display. The method includes: obtaining low visual fatigue parameter information on a frame section including at least one frame of a received 3D image; obtaining disparity vector information on each frame of the 3D image; and determining a disparity minimum limit value and a disparity maximum limit value with respect to the 3D image.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/178,217 filed on Jul. 23, 2008 in the U.S. Patent and TrademarkOffice, which claims priority from U.S. Provisional Application No.60/978,809, filed on Oct. 10, 2007 in the U.S. Patent and TrademarkOffice, and Korean Patent Application No. 10-2007-0121397, filed on Nov.27, 2007, in the Korean Intellectual Property Office, and thedisclosures of which are incorporated herein in their entirety byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Methods and apparatuses consistent with the present invention relate toreducing fatigue resulting from viewing a three-dimensional (3D) imagedisplay, and more particularly, to reducing fatigue by adjustingdisparity in order to avoid a viewer's fatigue due to a disparity vectorrange of a 3D image, and to generating a 3D image data stream includinglow visual fatigue parameter information necessary for reducing thefatigue.

2. Description of the Related Art

Owing to the development of high performance display devices and to thesupport of a fast communication environment, commercialization of 3Dimage display systems is expected. However, user fatigue resulting fromviewing a 3D image display is emerging as a serious problem.

An artificially realized image depth is presented through 3D effects,and thus viewers perceive fuzzy 3D effects or feel dizzy and suffer fromfatigue due to the artificial image depth.

Therefore, when a user observes 3D images but is not satisfied with theappearance of the image depth of the images, the user may feel dizzy orsuffer from eye fatigue. User fatigue resulting from viewing a 3D imagedisplay may manifest in various physiological forms, such as visualfatigue, dizziness, vomiting, or the like.

These forms of fatigue greatly hinder the widespread proliferation of 3Dimage displays.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide a method andapparatus for reducing fatigue by measuring disparity limit values thatcause a user to experience fatigue from viewing a 3D image display andby adjusting a disparity so that a disparity vector range of a 3D imagedoes not exceed the disparity limit values.

Exemplary embodiments of the present invention also provide a method andapparatus for generating a 3D image data stream including low visualfatigue parameter information so as to reduce a user's fatigue resultingfrom viewing a 3D image display. Throughout the specification, thelanguage “record” or “recording” means “insert” or “inserting”.

According to an aspect of the present invention, there is provided amethod of reducing fatigue resulting from viewing a 3D image display,the method comprising: obtaining low visual fatigue parameterinformation with respect to a frame section including at least one frameof a received 3D image; obtaining disparity vector information withrespect to each frame of the 3D image; determining disparity limitvalues that are a disparity minimum limit value and a disparity maximumlimit value with respect to the 3D image; and comparing the determineddisparity limit values with the obtained disparity vector informationand adjusting a disparity of the 3D image.

The obtaining the disparity vector information may comprise extractingthe disparity vector information from a low visual fatigue parameter,wherein the disparity vector information includes a disparity vectorminimum value and a disparity vector maximum value of the frame section.

The obtaining the disparity vector information may further comprisedetermining the disparity vector minimum value and the disparity vectormaximum value of the frame section by applying a disparity estimationmethod to the 3D image.

The determining the disparity limit values may comprise: determining aviewing distance and a distance between both eyes of a user; determininga parallax angle between both eyes by using the viewing distance and thedistance between both eyes; determining a pixel size value of thedisplay device by using at least one of a horizontal size and a verticalsize of the display device and a resolution thereof; and determiningdisparity minimum and maximum limit values by using at least one of theparallax angle between both eyes, the pixel size value of the displaydevice, the distance between both eyes, and the viewing distance.

The determining the disparity limit values may further compriseextracting at least one of the viewing distance and the horizontal andvertical sizes of the display device from the low visual fatigueparameter.

The determining the disparity limit values may further comprise, if theextracted viewing distance differs from a substantial viewing distance,and the pixel size value of the display device that is determinedaccording to the horizontal and vertical sizes of the display devicediffers from a pixel size value of a substantial display device,determining the parallax angle between both eyes and the disparitymaximum and minimum limit values by using the pixel size value of thesubstantial display device.

The adjusting the disparity of the 3D image may comprise comparing arange of disparity limit values with a range of the obtained disparityvectors, wherein the range of disparity limit values is a range betweenthe disparity maximum and minimum limit values, and the range of thedisparity vectors is a range between minimum and maximum values of theobtained disparity vectors.

The adjusting the disparity of the 3D image may further comprise, if therange of the disparity vectors extends beyond the range of the disparitylimit values in a predetermined direction by N pixels, parallel movingthe 3D image in a direction opposite to the predetermined direction by Npixels.

The adjusting the disparity of the 3D image may further comprise, if asize of the range of the disparity vectors is greater than a size of therange of the disparity limit values, reducing the 3D image by a ratio kwhen the ratio k is used to reduce the size of the range of thedisparity vectors smaller than the size of the range of the disparitylimit values.

The low visual fatigue parameter information may be extracted from anInternational Standard Organization (ISO)-based media file format if the3D image data stream is the ISO-based media file format.

The ISO-based media file format may include a moov box, an mdat box, anda meta box, wherein the low visual fatigue parameter information isextracted from at least one of a lower level box of the meta box, alower level box of the moov box, a lower level box of a trak box that isa lower level box of the moov box, a lower level box of a trak box, anda lower level box of a meta box that is the lower level box of the trakbox.

The method may further comprising: searching for reproductioninformation of the 3D image including size information of the displaydevice necessary for the 3D image set by a service server providing the3D image, from the service server; and if the size information of thedisplay device necessary for the 3D image set by the service server isthe same as a substantial 3D image display device for reproducing the 3Dimage, selecting the 3D image.

If the size information of the display device necessary for the 3D imageset by the service server differs from the substantial 3D image displaydevice for reproducing the 3D image, the obtaining of the low visualfatigue parameter information further comprises obtaining fatiguereduction operation information indicating whether a viewing fatiguereduction operation can be performed from the low visual fatigueparameter information, the disparity limit values are determined if itis confirmed that the viewing fatigue reduction operation can beperformed according to the fatigue reduction operation information,further comprising: if it is confirmed that the viewing fatiguereduction operation cannot be performed according to the fatiguereduction operation information, the display device outputting a warningmessage and confirming whether to reproduce the 3D image.

According to another aspect of the present invention, there is providedan apparatus for reducing fatigue resulting from viewing a 3D imagedisplay, the apparatus comprising: a low visual fatigue parameterinformation obtaining unit which obtains low visual fatigue parameterinformation with respect to a frame section including at least one frameof a received 3D image; a disparity vector information obtaining unitwhich obtains disparity vector information with respect to each frame ofthe 3D image; a disparity limit values determining unit which determinesdisparity limit values that are a disparity minimum limit value and adisparity maximum limit value with respect to the 3D image; and adisparity adjusting unit which compares the determined disparity limitvalues with the obtained disparity vector information and adjusts adisparity of the 3D image.

The disparity vector information obtaining unit may extract thedisparity vector information from a low visual fatigue parameter,wherein the disparity vector information includes a disparity vectorminimum value and a disparity vector maximum value of the frame section.

The disparity vector information obtaining unit may determine thedisparity vector minimum value and the disparity vector maximum value ofthe frame section by applying a disparity estimation method to the 3Dimage.

The disparity limit values determining unit may determine a viewingdistance and a distance between both eyes of a user, determine aparallax angle between both eyes by using the viewing distance and thedistance between both eyes, determine a pixel size value of the displaydevice by using at least one of a horizontal size and a vertical size ofthe display device and a resolution thereof, and determine disparityminimum and maximum limit values by using at least one of the parallaxangle between both eyes, the pixel size value of the display device, thedistance between both eyes, and the viewing distance.

The disparity adjusting unit may compare a range of disparity limitvalues with a range of the obtained disparity vectors, if the range ofthe disparity vectors extends beyond the range of the disparity limitvalues in a predetermined direction by N pixels, may move the 3D imagein a direction parallel to and opposite to the predetermined directionby the N pixels, and, if a size of the range of the disparity vectors isgreater than a size of the range of the disparity limit values, mayreduce the 3D image by a ratio k when the ratio k is used to reduce thesize of the range of the disparity vectors smaller than the size of therange of the disparity limit values, wherein the range of disparitylimit values is a range between the disparity maximum and minimum limitvalues, and the range of the disparity vectors is a range betweenminimum and maximum values of the obtained disparity vectors.

According to another aspect of the present invention, there is provideda method of generating a 3D image data stream including 3D image data,the method comprising: performing disparity estimation with respect toframes of the 3D image and determining disparity vectors; recording the3D image data onto a payload area of the 3D image data stream; andrecording a low visual fatigue parameter including at least one of thehorizontal and the vertical size of a display device, a viewingdistance, information on the determined disparity vectors, and fatiguereduction operation information indicating whether a view fatiguereduction operation can be performed onto a header area of the lowvisual fatigue 3D image data stream, as a parameter of a frame sectionincluding at least one frame of the 3D image.

The information on the determined disparity vectors may include at leastone of a disparity minimum value that is a minimum value of disparityvectors of the frame section and a disparity maximum value that is amaximum value of disparity vectors of the frame section, from among thedetermined disparity vectors.

The recording the low visual fatigue parameter may comprise recordingthe low visual fatigue parameter information onto an ISO-based mediafile format if the 3D image data stream is the ISO-based media fileformat.

The ISO-based media file format may include a moov box, an mdat box, anda meta box, wherein the recording of the low visual fatigue parametercomprises recording the low visual fatigue parameter information onto atleast one of a lower level box of a meta box, a lower level box of amoov box, a lower level box of a trak box that is a lower level box ofthe moov box, a lower level box of a trak box, and a lower level box ofa meta box that is the lower level box of the trak box.

According to another aspect of the present invention, there is providedan apparatus for generating a 3D image data stream including 3D imagedata, the apparatus comprising: a disparity vector determining unitwhich performs disparity estimation with respect to frames of the 3Dimage and determining disparity vectors; a 3D image data recording unitwhich records the 3D image data onto a payload area of the 3D image datastream; and a low visual fatigue parameter recording unit which recordsa low visual fatigue parameter including at least one of a horizontaland vertical size of a display device, a viewing distance, informationon the determined disparity vectors, and fatigue reduction operationinformation indicating whether a view fatigue reduction operation can beperformed onto a header area of the low visual fatigue 3D image datastream, as a parameter of a frame section including at least one frameof the 3D image.

The information on the determined disparity vectors may include at leastone of a disparity minimum value that is a minimum value of disparityvectors of the frame section and a disparity maximum value that is amaximum value of disparity vectors of the frame section from among thedetermined disparity vectors.

According to another aspect of the present invention, there is provideda computer readable recording medium having recorded thereon a programfor executing the method of reducing fatigue resulting from viewing athree-dimensional (3D) image display.

According to another exemplary embodiment of the present invention,there is provided a computer readable recording medium having recordedthereon a program for executing the method of generating a 3D image datastream including 3D image data.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will become moreapparent by the following detailed description of exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a block diagram of an apparatus for reducing fatigue resultingfrom viewing a 3D image display according to an exemplary embodiment ofthe present invention;

FIG. 2 is a block diagram of an apparatus for generating a low visualfatigue 3D image data stream according to an exemplary embodiment of thepresent invention;

FIG. 3 is a diagram for explaining a method of determining minimum andmaximum display limit values according to an exemplary embodiment of thepresent invention;

FIG. 4 illustrates an ideal distribution of disparity vectors;

FIG. 5A illustrates an exemplary distribution of disparity vectors in apositive direction;

FIG. 5B is a diagram for explaining an exemplary disparity adjustingmethod when disparity vectors are distributed in a positive direction;

FIG. 6A illustrates an exemplary distribution of disparity vectors in anegative direction;

FIG. 6B is a diagram for explaining an exemplary disparity adjustingmethod when disparity vectors are distributed in a negative direction;

FIG. 7A illustrates an exemplary range of disparity vectors exceeding arange of disparity limit values;

FIG. 7B is a diagram for explaining an exemplary disparity adjustingmethod when a range of disparity vectors exceeds a range of disparitylimit values;

FIG. 8 is a diagram of an International Standard Organization(ISO)-based media file format;

FIG. 9 is a diagram of a box list of the ISO-based media file formataccording to an exemplary embodiment of the present invention;

FIG. 10 illustrates a structure of a 3D low visual fatigue parameteraccording to an exemplary embodiment of the present invention;

FIG. 11A is a diagram for explaining a method of presenting a 3D lowvisual fatigue parameter in an ISO-based media file format according toan exemplary embodiment of the present invention;

FIG. 11B is a diagram for explaining a method of presenting a 3D lowvisual fatigue parameter in an ISO-based media file format according toanother exemplary embodiment of the present invention;

FIG. 12 is a flowchart of a method of reducing fatigue resulting fromviewing a 3D image display according to an exemplary embodiment of thepresent invention; and

FIG. 13 is a flowchart of a method of generating a low visual fatigue 3Dimage data stream according to an exemplary embodiment of the presentinvention.

FIG. 14 is a block diagram of a stereoscopic image file generationsystem using a stereoscopic image datastream generation method,according to an embodiment of the present invention.

FIG. 15 is a block diagram of a stereoscopic imagerestoration/reproduction system using a stereoscopic image restorationmethod, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

Hereinafter, the present invention will be described more fully withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown.

FIG. 1 is a block diagram of an apparatus 100 for reducing fatigueresulting from viewing a 3D image display according to an exemplaryembodiment of the present invention. Referring to FIG. 1, the apparatus100 for reducing fatigue resulting from viewing the 3D image displaycomprises a low visual fatigue parameter information obtaining unit 110,a disparity vector information obtaining unit 120, a disparity limitvalues determining unit 130, and a disparity adjusting unit 140.

The low visual fatigue parameter information obtaining unit 110 obtainslow visual fatigue parameter information with respect to a frame sectionincluding one or more frames of a received 3D image. The unit 110outputs the low visual fatigue parameter information to the disparityvector information obtaining unit 120 and the disparity limit valuesdetermining unit 130.

The low visual fatigue parameter is a parameter used for or supportingprediction of a degree of fatigue that occurs when a user watches 3Dimage content. In the present embodiment, examples of low visual fatigueparameters are the size of a display screen, a viewing distance, maximumand minimum disparity values of content, and the like.

In the present exemplary embodiment, the low visual fatigue parameterinformation can be determined per frame section including one or moreframes. Therefore, when a frame section includes all frames, althoughthe same low visual fatigue parameter information may be applied to allframes, different types of low visual fatigue parameter information maybe applied to some frames.

The disparity vector information obtaining unit 120 obtains disparityvector information from the low visual fatigue parameter informationreceived from the low visual fatigue parameter information obtainingunit 110 and from the received 3D image, and outputs the disparityvector information to the disparity adjusting unit 140.

The disparity vector information obtaining unit 120 extracts thedisparity vector information from a low visual fatigue parameter. Thedisparity vector information includes maximum and minimum disparityvector values of a frame section. When the same low visual fatigueparameter is applied to all frame sections, the disparity vectorinformation may include average values of minimum and maximum values ofdisparity vectors of all frames.

Alternatively, the disparity vector information obtaining unit 120 mayapply a disparity estimation method to the received 3D image anddetermine minimum and maximum disparity values of a frame section. Whenthe same low visual fatigue parameter is applied to all frame sections,the disparity vector information may include average values of minimumand maximum values of disparity vectors of all frames.

The disparity limit values determining unit 130 receives the low visualfatigue parameter information from the low visual fatigue parameterinformation obtaining unit 110, determines disparity limit values thatare minimum and maximum disparity limit values of the received 3D image,and outputs the disparity limit values to the disparity adjusting unit140.

The disparity limit values determining unit 130 determines a viewingdistance and a distance between both eyes of a user and determines aviewing angle of both eyes by using the distances between the user andthe display screen and between both eyes. The disparity limit valuesdetermining unit 130 determines pixel size values of a display device byusing at least one of the horizontal and vertical size of the displaydevice and the resolution thereof. Alternatively, the disparity limitvalues determining unit 130 determines the minimum and maximum displaylimit values by using at least one of the viewing angle of both eyes,the distances between the user and the display device and between botheyes, and the pixel size values of the display device. A method ofdetermining the display limit values corresponding to the minimum andmaximum display limit values will be described with reference to FIG. 3.

The disparity limit values determining unit 130 detects at least one ofthe viewing distance and the horizontal and vertical size of the displayscreen from the low visual fatigue parameter information.

Alternatively, when the detected viewing distance differs from asubstantial viewing distance, and the pixel size values of the displaydevice determined according to the detected horizontal and vertical sizeof the display device differ from substantial pixel size values of thedisplay device, the disparity limit values determining unit 130 maydetermine the viewing angle of both eyes and the minimum and maximumdisplay limit values by using the substantial pixel size values of thedisplay device.

The disparity adjusting unit 140 receives the disparity limit valuesfrom the disparity limit values determining unit 130, compares thedisparity limit values determining unit 130 with the disparity vectorinformation, and adjusts a disparity of the received 3D image.

The disparity adjusting unit 140 compares a disparity limit value rangewith a disparity vector average value range. The disparity limit valuerange is a range between a minimum disparity limit value and a maximumdisparity limit. The disparity vector average value range is a rangebetween an average value of minimum values and an average value ofmaximum values of obtained disparity vectors.

As a result of comparing the disparity limit value range with thedisparity vector average value range, if the disparity vector averagevalue range exceeds the disparity limit value range by N pixels in apredetermined direction, the disparity adjusting unit 140 moves thereceived 3D image by the N pixels in a direction parallel to butopposite to the predetermined direction

If the disparity vector average value range is greater than thedisparity limit value range, the disparity adjusting unit 140 reducesthe received 3D image by a ratio k when the ratio k is used to reducethe disparity vector average value range so as to be smaller than thedisparity limit value range.

The apparatus 100 for reducing fatigue resulting from viewing the 3Dimage display extracts the low visual fatigue parameter from anISO-based media file format when the 3D image data stream is in theISO-based media file format.

Alternatively, when the 3D image data stream is in the ISO-based mediafile format, examples of the ISO-based media file format include a moovbox, a mdat box, and a meta box. The low visual fatigue parameterinformation including the disparity vector information for adjusting thedisparity may be extracted from at least one of a lower level box of themeta box, a lower level box of the moov box, a lower level box of a trakbox that is a lower level box of the moov box, a lower level box of atrak box, and a lower level box of a meta box that is the lower levelbox of the trak box.

FIG. 2 is a block diagram of an apparatus 200 for generating a lowvisual fatigue 3D image data stream according to an exemplary embodimentof the present invention. Referring to FIG. 2, the apparatus 200 forgenerating a low visual fatigue 3D image data stream comprises adisparity vector determining unit 210, a 3D image data recording unit220, and a low visual fatigue parameter recording unit 230.

The disparity vector determining unit 210 applies a disparity estimationmethod to a 3D image to determine a disparity vector. The disparityestimation method of this embodiment is the conventional disparityestimation method and thus its description will not be repeated here.

The 3D image data recording unit 220 records 3D image data onto apayload area of the 3D image data stream.

The low visual fatigue parameter recording unit 230 records a low visualfatigue parameter including at least one of the horizontal and verticalsize of a display device, a viewing distance, and information on thedetermined disparity vector onto a header area of the 3D image datastream as a parameter of a frame section including one or more frames ofa 3D image.

When the 3D image data stream is in an ISO-based media file format, thelow visual fatigue parameter recording unit 230 may record the lowvisual fatigue parameter information onto the ISO-based media fileformat stream.

Alternatively, when the 3D image data stream is in the ISO-based mediafile format and includes a moov box, a mdat box, and a meta box, the lowvisual fatigue parameter recording unit 230 may record multi-view cameraparameter information onto at least one of a lower level box of the metabox, a lower level box of the moov box, a lower level box of a trak boxthat is a lower level box of the moov box, a lower level box of a trakbox, and a lower level box of the meta box that is the lower level boxof the trak box.

FIG. 3 is a diagram for explaining a method of determining the minimumand maximum display limit values according to an exemplary embodiment ofthe present invention. Referring to FIG. 3, a method of operating thedisparity limit value determining unit 130 will now be described.

Since fatigue may result from viewing 3D images, the safetyspecification of the Japanese 3D consortium has suggested a parallaxangle range of a screen display within ±1°. The parallax angle is adifference between an adjustment angle 330 α and convergence angles 340β and 350 γ. Hence, the parallax angle range of the present embodimentis within ±1°.

Since a disparity by the parallax angle is presented on a display screen300 in a pixel unit, a disparity limit value range is determined by thepixel size of the display screen 300, and the pixel size is determinedaccording to the size and resolution of the display screen 300. Adistance 310 between a user and the display screen 300 and a distance320 between both eyes of the user are needed to know the parallax angle.That is, trigonometry using the distance 310 between the user and thedisplay screen 300 and the distance 320 between both eyes of the usercan be used to calculate the adjustment angle 330 α. Differences betweenthe convergence angles 340 β and 350 γ and the adjustment angle 330 αare set to −1° and +1° in order to make the parallax angle within ±1°.

Hereinafter a process of calculating a disparity limit value will now bedescribed.

When the size and resolution of the display screen 300 are 2.5 inchesand 320×240, respectively, the pixel size of the display screen 300 is0.159 mm. Generally, the distance 310 between the user and the displayscreen 300 and the distance 320 between both eyes are set to 300 mm and65 mm, respectively. The adjustment angle 330 α is 12.37° according tothe trigonometry using the distance 310 between the user and the displayscreen 300 and the distance 320 between both eyes of the user.Therefore, the convergence angles 340 β and 350 γ are 11.37° and 13.37°,respectively.

According to the trigonometry using the distance 320 between both eyes,disparities 345 and 355 caused by the convergence angles 340 β and 350 γare 5.73 mm and 5.32 mm, respectively. The limit values of thedisparities 345 and 355 are determined as +36 pixels and −33 pixels.

Alternatively, when the size of the display screen 300 is 3.5 inches,since the pixel size of the display screen 300 is 0.219 mm, the limitvalues of the disparities 345 and 355 are determined as +26 pixels and−24 pixels on a display screen having the size of 2.5 inches.

A 3D content display based on the disparity limit values stated aboveconfirms that a change in the size of a 3D display screen can change thedisparity limit values. A large disparity of 3D content displayed on asmall 3D display screen causes only a little fatigue, whereas the samecontent displayed on a large 3D display screen may cause a great deal offatigue.

Therefore, a content creator provides display information optimized to3D content when creating the 3D content, so that the user can search forthe 3D content from a service server and select a 3D image causing lessfatigue.

When the size optimized according to the 3D content that the user is toproduce and the size of a terminal differ from each other, if there is adevice or a recording medium for performing a fatigue reducing method,the fatigue reducing method is performed, and, if not, a warning messageis displayed to ask the user whether to reproduce the 3D content.

FIG. 4 illustrates an ideal distribution of disparity vectors. Referringto FIG. 4, a maximum disparity vector value 450 and a minimum disparityvector value 460 of a 3D image are within the range between a disparityminimum limit value 410 and a disparity maximum limit value 420, and itis ideal that a range 470 of disparity vectors does not exceed a range430 of the disparity limit values. In this case, a post-process is notneeded to adjust disparity of the 3D image.

In the present embodiment, disparity vector information is extractedfrom header information of a received 3D image data stream in order tocalculate disparity vectors. Alternatively, a disparity estimationmethod may be applied to the received 3D image to directly determinedisparity vectors.

FIG. 5A illustrates a distribution of disparity vectors in a positivedirection. Referring to FIG. 5A, a range 530 of disparity vectors doesnot exceed the range 430 of the disparity limit values, a minimum value510 of disparity vectors is within the disparity minimum limit value 410and the disparity maximum limit value 420, and a maximum value 520 ofdisparity vectors extends in the positive direction by N pixels beyondthe disparity minimum limit value 410 and the disparity maximum limitvalue 420.

The disparity adjusting unit 140 can move the range 530 of disparityvectors in a negative direction by the N pixels so as to be adjusted toa minimum value 550 and a maximum value 560 of disparity vectors, sothat the minimum value 510 and the maximum value 520 of disparityvectors are within the disparity minimum limit value 410 and thedisparity maximum limit value 420.

FIG. 5B is a diagram for explaining an exemplary disparity adjustingmethod when disparity vectors are distributed in a positive direction.Referring to FIG. 5B, since disparity vectors of a left viewpoint image570 and a right viewpoint image 575 of a 3D image are distributed in apositive direction by N pixels, the disparity adjusting unit 140 movesboth the left viewpoint image 570 and the right viewpoint image 575 in anegative direction by the N pixels to adjust disparity of the 3D image.Therefore, the disparity adjusting unit 140 can move the left viewpointimage 570 and the right viewpoint image 575 in the negative directionand generate a disparity adjusted left viewpoint image 580 and adisparity adjusted right viewpoint image 585, respectively.

FIG. 6A illustrates a distribution of disparity vectors in a negativedirection. Referring to FIG. 6A, a range 630 of disparity vectors doesnot exceed the range 430 of the disparity limit values, a minimum value610 of disparity vectors is within the disparity minimum limit value 410and the disparity maximum limit value 420, and a maximum value 620 ofdisparity vectors extends in the negative direction by N pixels beyondthe disparity minimum limit value 410 and the disparity maximum limitvalue 420.

According to another exemplary embodiment, the range 630 of disparityvectors is moved in a positive direction by the N pixels so as to beadjusted to a minimum value 650 and a maximum value 660 of disparityvectors, so that the minimum value 610 and the maximum value 620 ofdisparity vectors are within the disparity minimum limit value 410 andthe disparity maximum limit value 420.

FIG. 6B is a diagram for explaining an exemplary disparity adjustingmethod when disparity vectors are distributed in a negative direction.Referring to FIG. 6B, since disparity vectors of a left viewpoint image670 and a right viewpoint image 675 of a 3D image are distributed in anegative direction by N pixels, the disparity adjusting unit 140 movesboth the left viewpoint image 670 and the right viewpoint image 675 in apositive direction by the N pixels so as to adjust disparity of the 3Dimage. Therefore, the disparity adjusting unit 140 can move the leftviewpoint image 670 and the right viewpoint image 675 in the positivedirection and generate a disparity adjusted left viewpoint image 680 anda disparity adjusted right viewpoint image 685, respectively.

FIG. 7A illustrates a range 730 of disparity vectors exceeding the range430 of disparity limit values. Referring to FIG. 7A, the range 730 ofdisparity vectors exceeds the range 430 of the disparity limit values, aminimum value 710 of disparity vectors is not within the disparityminimum limit value 410 and the disparity maximum limit value 420 but amaximum value 720 of disparity vectors extends beyond the disparityminimum limit value 410 and the disparity maximum limit value 420.

In this case, a parallel movement of disparity vectors cannot allow theminimum value 710 and the maximum value 720 of disparity vectors to bewithin the disparity minimum limit value 410 and the disparity maximumlimit value 420. The disparity adjusting unit 140 can reduce the range730 of disparity vectors so as not to exceed the range 430 of thedisparity limit values in order to adjust disparity of the 3D image.

In more detail, if the range 730 of disparity vectors and an adjustedrange 770 of disparity vectors are a and b, respectively, the range 730of disparity vectors is reduced to a:b so that the minimum value 710 andthe maximum value 720 of disparity vectors can be adjusted to a minimumvalue 750 and a maximum value 760 of disparity vectors.

FIG. 7B is a diagram for explaining a disparity adjusting method when arange of disparity vectors exceeds the range of disparity limit values.Referring to FIG. 7B, since the range of disparity vectors of a leftviewpoint image 780 and a right viewpoint image 785 of a 3D imageexceeds the range of disparity limit values, the disparity adjustingunit 140 reduces both the left viewpoint image 780 and the rightviewpoint image 785 so as to adjust disparity so that the range ofdisparity vectors does not exceed the range of disparity limit values.Therefore, the disparity adjusting unit 140 can reduce the leftviewpoint image 780 and the right viewpoint image 785 to a:b andgenerate a disparity adjusted left viewpoint image 790 and a disparityadjusted right viewpoint image 795.

FIG. 8 is a diagram of an ISO-based media file format. Referring to FIG.8, an ISO file box 800 comprises a moov box 810 and an mdat box 820.

The moov box 810 includes basic header information on video traks oraudio traks. The mdat box 820 includes substantial video data or audiodata. Alternatively, the mdat box 820 includes interleaved time-orderedvideo or audio frames.

FIG. 9 is a diagram of a box list of the ISO-based media file formataccording to an exemplary embodiment of the present invention. Referringto FIG. 9, an ftyp box 910 indicates a file type and compatibility andincludes information on a major brand of a file. In the presentembodiment, the major brand of the file is set as “ssav” indicating thatthe file is a 3D stereo image. The “ssav” is an abbreviation ofstereoscopic audio-video (AV).

A moov box 920 is a space for all pieces of metadata of timed resources.As described with reference to FIG. 8, the moov box 920 includes headerinformation or metadata necessary for substantial media data included inan mdat box 930.

The mdat box 930 is a space for media data as described with referenceto FIG. 8.

A meta box 940 is a space for metadata except for the moov box 920. Asaif box 950 can be included in a lower level of another meta box thatis a lower level of a trak box 970 other than the meta box 940 as aspace for 3D image low-fatigue parameter information in the presentembodiment.

Although not shown, the space for 3D image low-fatigue parameterinformation may be positioned in at least one of a lower level box ofthe meta box 940, a lower level box of the moov box 920, a lower levelbox 960 of a trak box that is a lower level box of the moov box 920, alower level box of a trak box, and a lower level box of the meta box 940that is the lower level box of the trak box.

Therefore, the disparity vector information obtaining unit 120 obtainsdisparity vector information from a low visual fatigue parameterextracted from the saif box 950.

The low visual fatigue parameter recording unit 230 records the lowvisual fatigue parameter in the saif box 950 of a header area of theISO-based media file format.

FIG. 10 illustrates a structure of a 3D low visual fatigue parameteraccording to an embodiment of the present invention. Referring to FIG.10, 3DParams 1010 indicates the 3D low visual fatigue parameter.

OptimalDisplayHorizontalSize (1020) indicates a horizontal size of adisplay screen optimized according to 3D image data.

OptimalDisplayVerticalSize (1025) indicates a vertical size of thedisplay screen optimized according to the 3D image data.

OptimalViewDistance (1030) indicates a viewing distance optimizedaccording to the 3D image data.

MinDisparity (1040) indicates a minimum disparity vector value of aframe section of a 3D image.

MaxDisparity (1050) indicates a maximum disparity vector value of theframe section of the 3D image.

As described with reference to FIG. 3, the disparity limit valuesdetermining unit 130 determines disparity limit values using the viewingdistance and the size of the display screen that are optimized accordingto the 3D image, and, if the viewing distance or the size of the displayscreen changes, adaptively determines the disparity limit values byusing trigonometry in relation to the viewing distance or the size ofthe display screen that is optimized according to the 3D image.

When the disparity adjusting unit 140 obtains the disparity vectorinformation from the low visual fatigue parameter, the MinDisparity(1040) can be set as the minimum disparity vector value and theMaxDisparity (1050) can be set as the maximum disparity vector value.

FIG. 11A is a diagram for explaining a method of presenting a 3D lowvisual fatigue parameter in an ISO-based media file format according toan exemplary embodiment of the present invention. Referring to FIG. 11A,a low visual fatigue parameter presentation syntax corresponds to thesaif box 950 (Box type: ‘saif’) which is necessary for a 3Dmulti-viewpoint camera parameter, as shown in FIG. 9. It is notmandatory (Mandatory: No) to include a low visual fatigue parameter 1110in the ISO-based media file format. A parameter quantity is 0 or 1(Quantity: Zero or one). The definition of each parameter is the same asdescribed with reference to FIG. 10.

In the present embodiment, all frames of an image data stream are set asa frame section and are set to have the same low visual fatigueparameter 1110.

FIG. 11B is a diagram for explaining a method of presenting a 3D lowvisual fatigue parameter in an ISO-based media file format according toanother embodiment of the present invention. Referring to FIG. 11B, alow visual fatigue parameter 1160 varies according over time and is setfor each frame section including at least one frame.

A “for” syntax 1120 defines the low visual fatigue parameter 1160 foreach frame section. In more detail, identification information 1130(ES_ID) of a current basic stream, start frame location information 1140(offset) in the current basic stream, and the number of frames 1150(length) in the current basic stream are set for each frame section, sothat frame information on the current basic stream and a current framesection are set and the low visual fatigue parameter 1160 is set foreach frame section.

FIG. 12 is a flowchart of a method of reducing fatigue resulting fromviewing a 3D image display according to an exemplary embodiment of thepresent invention. Referring to FIG. 12, low visual fatigue parameterinformation with respect to a frame section including at least one frameof a received 3D image is obtained (operation 1210).

Disparity vector information with respect to each frame of the 3D imageis obtained (operation 1220).

The disparity vector information may be extracted from a low visualfatigue parameter and disparity estimation is performed with respect tothe 3D image so that the disparity vector information can be directlyobtained.

Disparity limit values that are minimum and maximum disparity limitvalues of the 3D image are determined (operation 1230).

The disparity limit values are determined by using trigonometry inrelation to a viewing distance, a distance between both eyes of a user,the horizontal and vertical size of the display screen, and resolutionof the display screen, and the like.

The disparity limit values and the disparity vector information arecompared so as to adjust disparity of the 3D image (operation 1240).

When a range size of disparity vectors is smaller than a range size ofthe disparity limit values and goes beyond the range size of thedisparity limit values, a parallel movement of disparity vectors enablesan adjustment of disparity.

According to another exemplary embodiment, when the range size ofdisparity vectors is greater than the range size of the disparity limitvalues, the 3D image is reduced so as to adjust disparity.

According to another exemplary embodiment, 3D image reproductioninformation including size information of a display device for a 3Dimage set by a service server providing the 3D image is searched for inthe service server. If the size information of the display device forthe 3D image set by the service server is the same as size informationof a substantial 3D image display device for reproducing the 3D image,the 3D image is selected.

If the size information of the display device for the 3D image set bythe service server is different from the size information of thesubstantial 3D image display device for reproducing the 3D image,fatigue reduction operation information indicating whether a viewfatigue reduction operation can be performed is obtained from the lowvisual fatigue parameter information.

If it is confirmed that the view fatigue reduction operation can beperformed based on the fatigue reduction operation information, anoperation for determining the disparity limit values is performed.Meanwhile, if it is confirmed that the view fatigue reduction operationcannot be performed based on the fatigue reduction operationinformation, the display device outputs a warning message and confirmswhether to reproduce the 3D image.

FIG. 13 is a flowchart of a method of generating a low visual fatigue 3Dimage data stream according to an exemplary embodiment of the presentinvention. Referring to FIG. 13, disparity estimation is performed withreference to frames of a 3D image and disparity vectors are determined(operation 1310).

3D image data is recorded onto a payload area of the low visual fatigue3D image data stream (operation 1320).

A low visual fatigue parameter including at least one of the horizontaland vertical size of a display device, a viewing distance, informationon the determined disparity vectors, and fatigue reduction operationinformation indicating whether a view fatigue reduction operation can beperformed is recoded onto a header area of the low visual fatigue 3Dimage data stream, as a parameter of a frame section including at leastone frame of the 3D image (operation 1330).

The information on the disparity vectors includes at least one of adisparity minimum value that is a minimum value of disparity vectors ofall frames and a disparity maximum value that is a maximum value ofdisparity vectors of all frames. FIG. 14 is a block diagram of astereoscopic image file generation system 1400 using a stereoscopicimage datastream generation method, according to an embodiment of thepresent invention.

Referring to FIG. 14, the stereoscopic image file generation system 1400includes a first view camera 1402, a second view camera 1404, amultiview/monoview image camera 1406, an input unit 1410, an imagesignal processing unit 1420, a storage unit 1430, an encoding unit 1440,and a file generation unit 1460.

The first and second view cameras 1402 and 1404 photograph apredetermined subject at first and second views so as to outputdifferent first and second view images, respectively. If a monoviewimage is also captured by the stereoscopic image file generation system1400, a monoscopic image is output from the multiview/monoview imagecamera 1406. An image output from each of the first and second viewcameras 1402 and 1404 and the multiview/monoview image camera 1406 isinput to the input unit 1410.

The image input to the input unit 1410 is pre-processed by the imagesignal processing unit 1420. For example, external image values, whichare analog values, are converted into digital values. Here, the externalimage values mean components of light and colors which are recognized bya sensor of a charge-coupled device (CCD) type or a complementarymetal-oxide semiconductor (CMOS) type.

The storage unit 1430 stores image data of the pre-processed image andprovides the image data to the encoding unit 1440. Although the storageunit 1430 is separately illustrated, the stereoscopic image filegeneration system 1400 may further include other storage elements forbuffering between the other elements of the stereoscopic image filegeneration system 1400, which are not the storage unit 1430.

The encoding unit 1440 encodes the image data received from the storageunit 1430. If necessary, the encoding of the image data by the encodingunit 1440 may be omitted.

The file generation unit 1460 inserts image correlation information 1450and the (encoded) image data received from the encoding unit 1440, intoa predetermined file format so as to generate an image file 1470. Theimage correlation information 1450 may include reference information ofa track box for representing correlations between images, and handlerinformation for representing a media type of each image.

Also, the image correlation information 1450 may include two-dimensional(2D) image-related information and three-dimensional (3D) image-relatedinformation. The 3D image-related information represents a correlationbetween the first and second view images, and may include information on2D/3D data sections, information on an arrangement method of the firstand second view images, information on an image file type, a cameraparameter, display information, and information on a disparity.

According to an embodiment of the present invention, the file generationunit 1460 may store the image data and the image correlation information1450 respectively in a media data region and a header region of theimage file 1470. If the image file 1470 is an ISO-based media fileformat, the image data may be stored in the form of an elementarystream, in an mdat box, and the image correlation information 1450 maybe stored in a trak box or any sub-level box of the trak box.

The image file 1470 is input or transmitted to a 3D image filereproduction apparatus.

FIG. 15 is a block diagram of a stereoscopic imagerestoration/reproduction system 1500 using a stereoscopic imagerestoration method, according to an embodiment of the present invention.

Referring to FIG. 15, the stereoscopic image restoration/reproductionsystem 1500 includes a file parsing unit 1520, a decoding unit 1530, astorage unit 1540, a reproduction unit 1550, and a display unit 1560.

The file parsing unit 1520 parses a received image file 1510. Afterinformation stored in each of a ftyp box, a moov box, a trak box, and ameta box is analyzed, image data stored in an mdat box may be extracted.First view image data 1522, second view image data 1524, andmultiview/monoview image data 1526 may be extracted as the image data.By parsing the image file 1510, image data-related information 1528 mayalso be extracted. The image data-related information 1528 may includecorrelation information between images, such as trak referenceinformation regarding related tracks.

The decoding unit 1530 receives and decodes the image data including thefirst view image data 1522, the second view image data 1524, and themultiview/monoview image data 1526 which are extracted from the imagefile 1510. The decoding is performed only if the image data in the imagefile 1510 has been encoded. The storage unit 1540 receives and stores(decoded) image data 1535 that is output from the decoding unit 1530,and the extracted image data-related information 1528 that is extractedby the file parsing unit 1520.

The reproduction unit 1550 receives image reproduction-relatedinformation 1548 and image data 1545 to be reproduced, from the storageunit 1540 so as to reproduce an image. The image reproduction-relatedinformation 1548 is information required to reproduce the image fromamong the image data-related information 1528, and includes imagecorrelation information.

The reproduction unit 1550 may reproduce the image data 1545 in a 2D or3D image reproduction method, by using the image reproduction-relatedinformation 1548. For example, the reproduction unit 1550 may combineand reproduce correlated stereoscopic images by referring to image dataidentification information. Also, the reproduction unit 1550 mayreproduce the correlated stereoscopic images and a monoscopic imagetogether, by referring to the image data identification information and2D/3D data section information.

The display unit 1560 may display the image reproduced by thereproduction unit 1550, on a screen. The display unit 1560 may be abarrier liquid crystal display (LCD). A monoscopic image may bedisplayed when the barrier LCD is turned off, and each view image of astereoscopic image may be displayed when the barrier LCD is turned on.

The present invention can also be embodied as computer readable code ona computer readable recording medium. The computer readable recordingmedium is any data storage device that can store data which can bethereafter read by a computer system. Examples of the computer readablerecording medium include read-only memory (ROM), random-access memory(RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storagedevices, and the like, as would be understood by one of skill in theart.

Methods and apparatuses for reducing fatigue resulting from viewing a 3Dimage display according to exemplary embodiments of the presentinvention measure disparity limit values that cause a user to experiencefatigue from viewing the 3D image display according to a viewingdistance, a distance between both eyes of the user, the size andresolution of a display device, and adjust a disparity so that adisparity vector range of a 3D image does not exceed the disparity limitvalues, thereby reducing the fatigue.

Furthermore, exemplary embodiments of the present invention canelaborately present low visual fatigue parameter information on each 3Dimage through a time-based low visual fatigue parameter per framesection unit.

Furthermore, exemplary methods and apparatuses for generating a datastream of a low visual fatigue 3D image according to embodiments of thepresent invention include low visual fatigue parameter information forreducing fatigue resulting from viewing a 3D image display on a headerarea of the 3D image data stream, thereby reducing the fatigue in anefficient manner. Hence, it is possible to view the 3D image for a longperiod of time.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. Theexemplary embodiments should be considered in descriptive sense only andnot for purposes of limitation. Therefore, the scope of the invention isdefined not by the detailed description of the invention but by theappended claims, and all differences within the scope will be construedas being included in the present invention.

What is claimed is:
 1. A method of reconstructing a stereoscopic imagefrom an image data stream in which stereoscopic image data is inserted,the method comprising: parsing the stereoscopic image data stream in anInternational Standard Organization (ISO)-based media file format, theISO-based media file format comprising a moov box, an mdat box, and ameta box; obtaining, from a first box in the meta box of thestereoscopic image data stream, low visual fatigue parameter informationwith respect to a frame section comprising at least one frame of areceived stereoscopic image from the stereoscopic image data stream;extracting at least one of horizontal size information and vertical sizeinformation of the display device predetermined with respect to thestereoscopic image from the low visual fatigue parameter information;extracting viewing distance information predetermined with respect tothe stereoscopic image from the low visual fatigue parameterinformation; and reconstructing the stereoscopic image using thestereoscopic image data extracted from the mdat box of the image datastream; wherein the low fatigue parameter is used for displaying thereconstructed stereoscopic image in a three dimensional display mode,and wherein the viewing distance information indicates a distancebetween the display device and a viewer.
 2. The method of claim 1,further comprising displaying the reconstructed stereoscopic image inthe three dimensional display mode using the at least one of horizontalsize information and vertical size information of the display device andthe viewing distance information.
 3. A method of reconstructing astereoscopic image from an image data stream in which stereoscopic imagedata is inserted, the method comprising: parsing the stereoscopic imagedata stream in an International Standard Organization (ISO)-based mediafile format, the ISO-based media file format comprising a moov box, anmdat box, and a meta box; obtaining, from a first box in the meta box ofthe stereoscopic image data stream, low visual fatigue parameterinformation with respect to a frame section comprising at least oneframe of a received stereoscopic image from the stereoscopic image datastream; extracting at least one of horizontal size information andvertical size information of the display device predetermined withrespect to the stereoscopic image from the low visual fatigue parameterinformation; extracting viewing distance information predetermined withrespect to the stereoscopic image from the low visual fatigue parameterinformation; extracting disparity vector information with respect todisparity vectors of each frame of the stereoscopic image; andreconstructing the stereoscopic image using the stereoscopic image dataextracted from the mdat box of the image data stream; wherein the lowfatigue parameter is used for displaying the reconstructed stereoscopicimage in a three dimensional display mode, and wherein the viewingdistance information indicates a distance between the display device anda viewer.
 4. The method of claim 3, further comprising displaying thereconstructed stereoscopic image in the three dimensional display modeusing the at least one of horizontal size information and vertical sizeinformation of the display device, the viewing distance information andthe disparity vector information.
 5. The method of claim 3, wherein thedisparity vector information comprises at least one of minimum valueinformation and maximum value information among values of disparityvectors between left-view right-view images.
 6. The method of claim 3,wherein the disparity vectors comprise at least one of a globaldisparity vector, a representative disparity vector, a foregrounddisparity vector and a background disparity vector between left-view andright-view images.
 7. A method of generating a stereoscopic image datastream in an ISO-based media file format, the ISO-based media fileformat comprising a moov box, an mdat box, and a meta box, the methodcomprising: inserting low visual fatigue parameter information withrespect to a frame section comprising at least one frame of stereoscopicimages into a first box in the meta box of the stereoscopic image datastream; and inserting the stereoscopic image data of the stereoscopicimages into the mdat box of the stereoscopic image data stream, whereinthe low visual fatigue parameter comprises at least one of a horizontaland vertical size of a display device and a viewing distancepredetermined with respect to the stereoscopic image and is used fordisplaying the reconstructed stereoscopic image in a three dimensionaldisplay mode, and wherein the viewing distance information indicates adistance between the display device and a viewer.
 8. A method ofgenerating a stereoscopic image data stream in an ISO-based media fileformat, the ISO-based media file format comprising a moov box, an mdatbox, and a meta box, the method comprising: inserting low visual fatigueparameter information with respect to a frame section comprising atleast one frame of stereoscopic images into a first box in the meta boxof the stereoscopic image data stream; and inserting the stereoscopicimage data of the stereoscopic images into the mdat box of thestereoscopic image data stream, wherein the low visual fatigue parametercomprises at least one of a horizontal and vertical size of a displaydevice and a viewing distance predetermined with respect to thestereoscopic image and is used for displaying the reconstructedstereoscopic image in a three dimensional display mode, and wherein theviewing distance information indicates a distance between the displaydevice and a viewer.
 9. The method of claim 8, wherein the disparityvector information comprises at least one of minimum value informationand maximum value information among values of disparity vectors betweenleft-view right-view images.
 10. The method of claim 8, wherein thedisparity vectors comprise at least one of a global disparity vector, arepresentative disparity vector, a foreground disparity vector and abackground disparity vector between left-view and right-view images.